Single-output and multiple-output boost DC-DC power converters are known. However, there is a continuing need to improve power conversion efficiency of known boost DC-DC power converters for example to improve battery life-time of portable applications. It would be advantageous to provide a boost DC-DC power converter where operational parameters of the power converters such as switching frequency and duty cycle are adjustable in dependence of various load specific requirements for example load power, load voltage, load current or other parameters associated with operation of the load.